How to password-protect a PDF
- 01
Add a PDF
Drop it in or pick it from your files.
- 02
Set a password
Type it twice, and choose what recipients may print, copy or change.
- 03
Protect and download
Save the encrypted PDF. It asks for the password whenever it’s opened.
Questions
Are my files uploaded anywhere?
No. LocalPDF runs entirely in your browser: files are read from your disk, processed on your device and saved straight back. Nothing is sent to a server, and once the page has loaded it keeps working with your internet connection switched off.
What encryption does it use?
AES-256, the standard security handler of PDF 2.0 (revision 6). Every string and stream in the file is encrypted, so nothing inside is readable without the password. It opens in any current reader: Acrobat X and later, Preview, Chrome, Edge and Firefox.
What if I forget the password?
There is no way to recover it. That is what makes the encryption worth anything: no back door, no reset, no support line. Save the password somewhere safe before you download the file.
How do the permission switches work?
Printing, copying and editing can be switched off for whoever opens the file. Acrobat and most readers honour these restrictions, and the owner password lifts them. Treat them as a polite request rather than a lock: anyone determined enough can strip them.
What protecting a PDF does, and when to use it
Protecting a PDF puts a password on the file itself. From then on, nothing inside — not one page, not a single word — can be read until the password is entered. It is the right tool for a contract with someone’s salary in it, a medical letter, a tax return, or anything that will travel by email or sit in a shared folder.
This tool encrypts with AES-256, the strongest scheme the PDF format defines, and the one every current reader understands. The whole document is rewritten: text, images, fonts, form fields and metadata are all encrypted. It also offers an optional owner password that lifts the printing, copying and editing restrictions, so a document can open freely while staying hard to copy.